server/handle.c

   1 /*
   2  * Server-side handle management
   3  *
   4  * Copyright (C) 1998 Alexandre Julliard
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2.1 of the License, or (at your option) any later version.
  10  *
  11  * This library is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with this library; if not, write to the Free Software
  18  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  19  */
  20
  21 #include "config.h"
  22 #include "wine/port.h"
  23
  24 #include <assert.h>
  25 #include <limits.h>
  26 #include <string.h>
  27 #include <stdio.h>
  28 #include <stdlib.h>
  29
  30 #include "winbase.h"
  31
  32 #include "handle.h"
  33 #include "process.h"
  34 #include "thread.h"
  35 #include "request.h"
  36
  37 struct handle_entry
  38 {
  39     struct object *ptr;       /* object */
  40     unsigned int   access;    /* access rights */
  41     int            fd;        /* file descriptor (in client process) */
  42 };
  43
  44 struct handle_table
  45 {
  46     struct object        obj;         /* object header */
  47     struct process      *process;     /* process owning this table */
  48     int                  count;       /* number of allocated entries */
  49     int                  last;        /* last used entry */
  50     int                  free;        /* first entry that may be free */
  51     struct handle_entry *entries;     /* handle entries */
  52 };
  53
  54 static struct handle_table *global_table;
  55
  56 /* reserved handle access rights */
  57 #define RESERVED_SHIFT         25
  58 #define RESERVED_INHERIT       (HANDLE_FLAG_INHERIT << RESERVED_SHIFT)
  59 #define RESERVED_CLOSE_PROTECT (HANDLE_FLAG_PROTECT_FROM_CLOSE << RESERVED_SHIFT)
  60 #define RESERVED_ALL           (RESERVED_INHERIT | RESERVED_CLOSE_PROTECT)
  61
  62 #define MIN_HANDLE_ENTRIES  32
  63
  64
  65 /* handle to table index conversion */
  66
  67 /* handles are a multiple of 4 under NT; handle 0 is not used */
  68 inline static obj_handle_t index_to_handle( int index )
  69 {
  70     return (obj_handle_t)((index + 1) << 2);
  71 }
  72 inline static int handle_to_index( obj_handle_t handle )
  73 {
  74     return ((unsigned int)handle >> 2) - 1;
  75 }
  76
  77 /* global handle conversion */
  78
  79 #define HANDLE_OBFUSCATOR 0x544a4def
  80
  81 inline static int handle_is_global( obj_handle_t handle)
  82 {
  83     return ((unsigned long)handle ^ HANDLE_OBFUSCATOR) < 0x10000;
  84 }
  85 inline static obj_handle_t handle_local_to_global( obj_handle_t handle )
  86 {
  87     if (!handle) return 0;
  88     return (obj_handle_t)((unsigned long)handle ^ HANDLE_OBFUSCATOR);
  89 }
  90 inline static obj_handle_t handle_global_to_local( obj_handle_t handle )
  91 {
  92     return (obj_handle_t)((unsigned long)handle ^ HANDLE_OBFUSCATOR);
  93 }
  94
  95
  96 static void handle_table_dump( struct object *obj, int verbose );
  97 static void handle_table_destroy( struct object *obj );
  98
  99 static const struct object_ops handle_table_ops =
 100 {
 101     sizeof(struct handle_table),     /* size */
 102     handle_table_dump,               /* dump */
 103     no_add_queue,                    /* add_queue */
 104     NULL,                            /* remove_queue */
 105     NULL,                            /* signaled */
 106     NULL,                            /* satisfied */
 107     NULL,                            /* get_poll_events */
 108     NULL,                            /* poll_event */
 109     no_get_fd,                       /* get_fd */
 110     no_flush,                        /* flush */
 111     no_get_file_info,                /* get_file_info */
 112     NULL,                            /* queue_async */
 113     handle_table_destroy             /* destroy */
 114 };
 115
 116 /* dump a handle table */
 117 static void handle_table_dump( struct object *obj, int verbose )
 118 {
 119     int i;
 120     struct handle_table *table = (struct handle_table *)obj;
 121     struct handle_entry *entry = table->entries;
 122
 123     assert( obj->ops == &handle_table_ops );
 124
 125     fprintf( stderr, "Handle table last=%d count=%d process=%p\n",
 126              table->last, table->count, table->process );
 127     if (!verbose) return;
 128     entry = table->entries;
 129     for (i = 0; i <= table->last; i++, entry++)
 130     {
 131         if (!entry->ptr) continue;
 132         fprintf( stderr, "%9u: %p %08x ",
 133                  (unsigned int)index_to_handle(i), entry->ptr, entry->access );
 134         entry->ptr->ops->dump( entry->ptr, 0 );
 135     }
 136 }
 137
 138 /* destroy a handle table */
 139 static void handle_table_destroy( struct object *obj )
 140 {
 141     int i;
 142     struct handle_table *table = (struct handle_table *)obj;
 143     struct handle_entry *entry = table->entries;
 144
 145     assert( obj->ops == &handle_table_ops );
 146
 147     for (i = 0; i <= table->last; i++, entry++)
 148     {
 149         struct object *obj = entry->ptr;
 150         entry->ptr = NULL;
 151         if (obj) release_object( obj );
 152     }
 153     free( table->entries );
 154 }
 155
 156 /* allocate a new handle table */
 157 struct handle_table *alloc_handle_table( struct process *process, int count )
 158 {
 159     struct handle_table *table;
 160
 161     if (count < MIN_HANDLE_ENTRIES) count = MIN_HANDLE_ENTRIES;
 162     if (!(table = alloc_object( &handle_table_ops, -1 )))
 163         return NULL;
 164     table->process = process;
 165     table->count   = count;
 166     table->last    = -1;
 167     table->free    = 0;
 168     if ((table->entries = mem_alloc( count * sizeof(*table->entries) ))) return table;
 169     release_object( table );
 170     return NULL;
 171 }
 172
 173 /* grow a handle table */
 174 static int grow_handle_table( struct handle_table *table )
 175 {
 176     struct handle_entry *new_entries;
 177     int count = table->count;
 178
 179     if (count >= INT_MAX / 2) return 0;
 180     count *= 2;
 181     if (!(new_entries = realloc( table->entries, count * sizeof(struct handle_entry) )))
 182     {
 183         set_error( STATUS_NO_MEMORY );
 184         return 0;
 185     }
 186     table->entries = new_entries;
 187     table->count   = count;
 188     return 1;
 189 }
 190
 191 /* allocate the first free entry in the handle table */
 192 static obj_handle_t alloc_entry( struct handle_table *table, void *obj, unsigned int access )
 193 {
 194     struct handle_entry *entry = table->entries + table->free;
 195     int i;
 196
 197     for (i = table->free; i <= table->last; i++, entry++) if (!entry->ptr) goto found;
 198     if (i >= table->count)
 199     {
 200         if (!grow_handle_table( table )) return 0;
 201         entry = table->entries + i;  /* the entries may have moved */
 202     }
 203     table->last = i;
 204  found:
 205     table->free = i + 1;
 206     entry->ptr    = grab_object( obj );
 207     entry->access = access;
 208     entry->fd     = -1;
 209     return index_to_handle(i);
 210 }
 211
 212 /* allocate a handle for an object, incrementing its refcount */
 213 /* return the handle, or 0 on error */
 214 obj_handle_t alloc_handle( struct process *process, void *obj, unsigned int access, int inherit )
 215 {
 216     struct handle_table *table = process->handles;
 217
 218     assert( table );
 219     assert( !(access & RESERVED_ALL) );
 220     if (inherit) access |= RESERVED_INHERIT;
 221     return alloc_entry( table, obj, access );
 222 }
 223
 224 /* allocate a global handle for an object, incrementing its refcount */
 225 /* return the handle, or 0 on error */
 226 static obj_handle_t alloc_global_handle( void *obj, unsigned int access )
 227 {
 228     if (!global_table)
 229     {
 230         if (!(global_table = (struct handle_table *)alloc_handle_table( NULL, 0 )))
 231             return 0;
 232     }
 233     return handle_local_to_global( alloc_entry( global_table, obj, access ));
 234 }
 235
 236 /* return a handle entry, or NULL if the handle is invalid */
 237 static struct handle_entry *get_handle( struct process *process, obj_handle_t handle )
 238 {
 239     struct handle_table *table = process->handles;
 240     struct handle_entry *entry;
 241     int index;
 242
 243     if (handle_is_global(handle))
 244     {
 245         handle = handle_global_to_local(handle);
 246         table = global_table;
 247     }
 248     if (!table) goto error;
 249     index = handle_to_index( handle );
 250     if (index < 0) goto error;
 251     if (index > table->last) goto error;
 252     entry = table->entries + index;
 253     if (!entry->ptr) goto error;
 254     return entry;
 255
 256  error:
 257     set_error( STATUS_INVALID_HANDLE );
 258     return NULL;
 259 }
 260
 261 /* attempt to shrink a table */
 262 static void shrink_handle_table( struct handle_table *table )
 263 {
 264     struct handle_entry *entry = table->entries + table->last;
 265     struct handle_entry *new_entries;
 266     int count = table->count;
 267
 268     while (table->last >= 0)
 269     {
 270         if (entry->ptr) break;
 271         table->last--;
 272         entry--;
 273     }
 274     if (table->last >= count / 4) return;  /* no need to shrink */
 275     if (count < MIN_HANDLE_ENTRIES * 2) return;  /* too small to shrink */
 276     count /= 2;
 277     if (!(new_entries = realloc( table->entries, count * sizeof(*new_entries) ))) return;
 278     table->count   = count;
 279     table->entries = new_entries;
 280 }
 281
 282 /* copy the handle table of the parent process */
 283 /* return 1 if OK, 0 on error */
 284 struct handle_table *copy_handle_table( struct process *process, struct process *parent )
 285 {
 286     struct handle_table *parent_table = parent->handles;
 287     struct handle_table *table;
 288     int i;
 289
 290     assert( parent_table );
 291     assert( parent_table->obj.ops == &handle_table_ops );
 292
 293     if (!(table = (struct handle_table *)alloc_handle_table( process, parent_table->count )))
 294         return NULL;
 295
 296     if ((table->last = parent_table->last) >= 0)
 297     {
 298         struct handle_entry *ptr = table->entries;
 299         memcpy( ptr, parent_table->entries, (table->last + 1) * sizeof(struct handle_entry) );
 300         for (i = 0; i <= table->last; i++, ptr++)
 301         {
 302             if (!ptr->ptr) continue;
 303             ptr->fd = -1;
 304             if (ptr->access & RESERVED_INHERIT) grab_object( ptr->ptr );
 305             else ptr->ptr = NULL; /* don't inherit this entry */
 306         }
 307     }
 308     /* attempt to shrink the table */
 309     shrink_handle_table( table );
 310     return table;
 311 }
 312
 313 /* close a handle and decrement the refcount of the associated object */
 314 /* return 1 if OK, 0 on error */
 315 int close_handle( struct process *process, obj_handle_t handle, int *fd )
 316 {
 317     struct handle_table *table;
 318     struct handle_entry *entry;
 319     struct object *obj;
 320
 321     if (!(entry = get_handle( process, handle ))) return 0;
 322     if (entry->access & RESERVED_CLOSE_PROTECT)
 323     {
 324         set_error( STATUS_INVALID_HANDLE );
 325         return 0;
 326     }
 327     obj = entry->ptr;
 328     entry->ptr = NULL;
 329     if (fd) *fd = entry->fd;
 330     else if (entry->fd != -1) return 1;  /* silently ignore close attempt if we cannot close the fd */
 331     entry->fd = -1;
 332     table = handle_is_global(handle) ? global_table : process->handles;
 333     if (entry < table->entries + table->free) table->free = entry - table->entries;
 334     if (entry == table->entries + table->last) shrink_handle_table( table );
 335     release_object( obj );
 336     return 1;
 337 }
 338
 339 /* close all the global handles */
 340 void close_global_handles(void)
 341 {
 342     if (global_table)
 343     {
 344         release_object( global_table );
 345         global_table = NULL;
 346     }
 347 }
 348
 349 /* retrieve the object corresponding to one of the magic pseudo-handles */
 350 static inline struct object *get_magic_handle( obj_handle_t handle )
 351 {
 352     switch((unsigned long)handle)
 353     {
 354         case 0xfffffffe:  /* current thread pseudo-handle */
 355             return &current->obj;
 356         case 0x7fffffff:  /* current process pseudo-handle */
 357         case 0xffffffff:  /* current process pseudo-handle */
 358             return (struct object *)current->process;
 359         default:
 360             return NULL;
 361     }
 362 }
 363
 364 /* retrieve the object corresponding to a handle, incrementing its refcount */
 365 struct object *get_handle_obj( struct process *process, obj_handle_t handle,
 366                                unsigned int access, const struct object_ops *ops )
 367 {
 368     struct handle_entry *entry;
 369     struct object *obj;
 370
 371     if (!(obj = get_magic_handle( handle )))
 372     {
 373         if (!(entry = get_handle( process, handle ))) return NULL;
 374         if ((entry->access & access) != access)
 375         {
 376             set_error( STATUS_ACCESS_DENIED );
 377             return NULL;
 378         }
 379         obj = entry->ptr;
 380     }
 381     if (ops && (obj->ops != ops))
 382     {
 383         set_error( STATUS_OBJECT_TYPE_MISMATCH );  /* not the right type */
 384         return NULL;
 385     }
 386     return grab_object( obj );
 387 }
 388
 389 /* retrieve the cached fd for a given handle */
 390 int get_handle_fd( struct process *process, obj_handle_t handle, unsigned int access )
 391 {
 392     struct handle_entry *entry;
 393
 394     if (!(entry = get_handle( process, handle ))) return -1;
 395     if ((entry->access & access) != access)
 396     {
 397         set_error( STATUS_ACCESS_DENIED );
 398         return -1;
 399     }
 400     return entry->fd;
 401 }
 402
 403 /* find the first inherited handle of the given type */
 404 /* this is needed for window stations and desktops (don't ask...) */
 405 obj_handle_t find_inherited_handle( struct process *process, const struct object_ops *ops )
 406 {
 407     struct handle_table *table = process->handles;
 408     struct handle_entry *ptr;
 409     int i;
 410
 411     if (!table) return 0;
 412
 413     for (i = 0, ptr = table->entries; i <= table->last; i++, ptr++)
 414     {
 415         if (!ptr->ptr) continue;
 416         if (ptr->ptr->ops != ops) continue;
 417         if (ptr->access & RESERVED_INHERIT) return index_to_handle(i);
 418     }
 419     return 0;
 420 }
 421
 422 /* get/set the handle reserved flags */
 423 /* return the old flags (or -1 on error) */
 424 int set_handle_info( struct process *process, obj_handle_t handle, int mask, int flags, int *fd )
 425 {
 426     struct handle_entry *entry;
 427     unsigned int old_access;
 428
 429     if (get_magic_handle( handle ))
 430     {
 431         /* we can retrieve but not set info for magic handles */
 432         if (mask) set_error( STATUS_ACCESS_DENIED );
 433         return 0;
 434     }
 435     if (!(entry = get_handle( process, handle ))) return -1;
 436     old_access = entry->access;
 437     mask  = (mask << RESERVED_SHIFT) & RESERVED_ALL;
 438     flags = (flags << RESERVED_SHIFT) & mask;
 439     entry->access = (entry->access & ~mask) | flags;
 440     /* if no current fd set it, otherwise return current fd */
 441     if (entry->fd == -1) entry->fd = *fd;
 442     *fd = entry->fd;
 443     return (old_access & RESERVED_ALL) >> RESERVED_SHIFT;
 444 }
 445
 446 /* duplicate a handle */
 447 obj_handle_t duplicate_handle( struct process *src, obj_handle_t src_handle, struct process *dst,
 448                            unsigned int access, int inherit, int options )
 449 {
 450     obj_handle_t res;
 451     struct object *obj = get_handle_obj( src, src_handle, 0, NULL );
 452
 453     if (!obj) return 0;
 454     if (options & DUP_HANDLE_SAME_ACCESS)
 455     {
 456         struct handle_entry *entry = get_handle( src, src_handle );
 457         if (entry)
 458             access = entry->access;
 459         else  /* pseudo-handle, give it full access */
 460         {
 461             access = STANDARD_RIGHTS_ALL | SPECIFIC_RIGHTS_ALL;
 462             clear_error();
 463         }
 464     }
 465     access &= ~RESERVED_ALL;
 466     if (options & DUP_HANDLE_MAKE_GLOBAL)
 467         res = alloc_global_handle( obj, access );
 468     else
 469         res = alloc_handle( dst, obj, access, inherit );
 470     release_object( obj );
 471     return res;
 472 }
 473
 474 /* open a new handle to an existing object */
 475 obj_handle_t open_object( const struct namespace *namespace, const WCHAR *name, size_t len,
 476                           const struct object_ops *ops, unsigned int access, int inherit )
 477 {
 478     obj_handle_t handle = 0;
 479     struct object *obj = find_object( namespace, name, len );
 480     if (obj)
 481     {
 482         if (ops && obj->ops != ops)
 483             set_error( STATUS_OBJECT_TYPE_MISMATCH );
 484         else
 485             handle = alloc_handle( current->process, obj, access, inherit );
 486         release_object( obj );
 487     }
 488     else
 489         set_error( STATUS_OBJECT_NAME_NOT_FOUND );
 490     return handle;
 491 }
 492
 493 /* close a handle */
 494 DECL_HANDLER(close_handle)
 495 {
 496     close_handle( current->process, req->handle, &reply->fd );
 497 }
 498
 499 /* set a handle information */
 500 DECL_HANDLER(set_handle_info)
 501 {
 502     int fd = req->fd;
 503
 504     if (handle_is_global(req->handle)) fd = -1;  /* no fd cache for global handles */
 505     reply->old_flags = set_handle_info( current->process, req->handle,
 506                                         req->mask, req->flags, &fd );
 507     reply->cur_fd = fd;
 508 }
 509
 510 /* duplicate a handle */
 511 DECL_HANDLER(dup_handle)
 512 {
 513     struct process *src, *dst;
 514
 515     reply->handle = 0;
 516     reply->fd = -1;
 517     if ((src = get_process_from_handle( req->src_process, PROCESS_DUP_HANDLE )))
 518     {
 519         if (req->options & DUP_HANDLE_MAKE_GLOBAL)
 520         {
 521             reply->handle = duplicate_handle( src, req->src_handle, NULL,
 522                                               req->access, req->inherit, req->options );
 523         }
 524         else if ((dst = get_process_from_handle( req->dst_process, PROCESS_DUP_HANDLE )))
 525         {
 526             reply->handle = duplicate_handle( src, req->src_handle, dst,
 527                                               req->access, req->inherit, req->options );
 528             release_object( dst );
 529         }
 530         /* close the handle no matter what happened */
 531         if (req->options & DUP_HANDLE_CLOSE_SOURCE)
 532         {
 533             if (src == current->process) close_handle( src, req->src_handle, &reply->fd );
 534             else close_handle( src, req->src_handle, NULL );
 535         }
 536         release_object( src );
 537     }
 538 }